The present invention relates generally to humidifiers and more particularly to evaporative humidifiers.
Humidifiers have been found to be very useful in raising the humidity of air present inside homes, particularly during periods of very dry weather or in winter, when outside air of low temperature is drawn inside a home and heated, causing the relative humidity within the home to be lowered to an uncomfortable level.
Various types or classes of humidifiers are well-known in the art. Examples of such include steam-type humidifiers, ultrasonic humidifiers, warm-air humidifiers and evaporative humidifiers. Steam-type humidifiers generally comprise a water container and an electric heating element submerged in the water, there being provided safety devices for switching off the current as soon as the water level drops below the heating element. A flow of hot steam is blown directly into the room to be humidified.
Ultrasonic humidifiers generally comprise a container filled with water which is brought to vibration by high-frequency vibrator means which causes the water to be atomized. An air stream directed onto the water surface carries the mist into the room to be humidified.
Warm-air humidifiers are similar to steam-type humidifiers in that water is heated to the boiling point. However, the steam generated by warm-air humidifiers is carried into a room as a mist mixed with air, at a temperature to be selected by judiciously choosing the ratio of steam to air.
Evaporative humidifiers generally include an open vessel containing a reservoir of cold water, a porous medium structure partly submerged in the cold water and a blower unit for drawing air through the porous medium structure. The porous medium is typically either (1) in the shape of a disc or a drum with part of the medium dipping into the water, the disc or drum being slowly rotated while air is blown through the portion above the water level, thus carrying humidity into the room; or (2) in the form of a stationary body adapted to draw water into the upper non-immersed part by capillary action, such as in the case of a wicking filter, the water on the upper non-immersed portion of the stationary body being discharged into the room by air blown therethrough.
In U.S. Pat. No. 4,225,542, inventors Wall et al., which issued Sep. 30, 1980, there is disclosed an evaporative humidifier with a humidification chamber of about 200 cc internal volume having an inlet connection port and an exit connection port for gases, a liquid reservoir and a removable porous evaporative element of open-ended cylindrical design which fits loosely within the humidification chamber when dry but which swells into good thermal contact with the side walls of the chamber when wet and which extends into the liquid reservoir. The chamber is tightly surrounded by a heating element so that heat is transferred directly to the chamber walls adjacent to the porous removable evaporative element and not to the liquid reservoir. The heating element is preferentially equipped with suitable electronic controls to monitor the heat transfer surface temperature, and to shut the unit off when said temperature exceeds a predetermined level. The humidifier is designed so that the gases reaching the patient will be at 100% relative humidity under most conditions of gas flow and heater temperature settings.
In U.S. Pat. No. 4,752,423, inventor Wong, which issued Jun. 21, 1988, there is described a combined humidifier and fan heater unit which includes a humidifier part electrically operable to dispense water vapor into the surrounding air space for humidifying purposes, and a fan heater part electrically operable either together with or instead of the humidifier part to draw air from the surrounding air space, through heating means, by which it is raised in temperature or not as desired, and passed back into the surrounding air space.
In U.S. Pat. No. 4,089,915, inventor Jackson, which issued May 16, 1978, there is described a self-sterilizing humidifier for air to be breathed, the humidifier being of the type having an endless porous media driven to be progressively immersed in a receptacle. Means are shown for periodically providing throughout the effective volume of water in the receptacle heated water at a temperature above about 180.degree. F. while the media drive is actuated, the heated water being sufficient to progressively expose the media to bacteria-killing conditions. In one embodiment a heater chamber automatically discharges a charge of water heated above about 180.degree. F. into the receptacle. In one such case a thermal actuator has sensitive parts exposed to water in both the heater chamber and the receptacle, the actuator releasing the charge when water in the receptacle lies below its sensitive part, and water in the heater chamber has reached or exceeds the selected high temperature. In another embodiment the heater element is in the receptacle and is periodically energized to maintain bacteria-killing conditions while the blower in the air flow path is de-energized to reduce evaporative cooling of the media and water during the sterilization interval.
In U.S. Pat. No. 5,037,586, inventors Mehrholz et al., which issued Aug. 6, 1991, there is described a humidifier which can be mounted in limited and a variety of different shaped spaces in a building such as a condominium or apartment, the humidifier comprising a centrifugal blower driven by an adjustable speed motor mounted in a cube-shaped module so that an outlet from the blower can be mounted on any selected side of the module such as any of the sidewalls or the top or bottom. A humidifier unit is selectively connectable to the centrifugal blower cube-shaped module and a preheater can be connected to the input of the humidifier. A water supply and drain can be connected to the humidifier and the output of the blower may be connected to the heat ducts to distribute the humidified air. Means are provided for mixing ambient air into the input of the blower, if desired. A drain safety switch may be provided to turn off the unit if the drain becomes clogged and also to remove excess water from the collecting pan. The unit may be connected to a remote digital electronic sensor humidistat having single or multiple stages or may include an integral humidistat in the unit.
In U.S. Pat. No. 3,193,261, inventor Nesbitt, which issued Jul. 6, 1965, there is described a humidifier designed to deliver air cleansed of air-borne particles, free of large water droplets and containing a maximum amount of moisture, the humidifier comprising a housing provided with relatively spaced air inlet and outlet openings that are separated by a baffle member which obstructs the direct flow of air from the air inlet opening to the air outlet opening. In passing through the humidifier, the circulated air, because of the baffle member and the relative positioning of the air inlet and outlet openings, is made to undergo a marked change in direction prior to being discharged from the humidifier. Atomizing means is also provided within the humidifier and is so positioned in the air stream as to generate a water vapor cloud upstream of the point at which the circulated air must undergo the marked change in direction. An air flow pattern is thus defined whereby air is drawn in through the air inlet opening, directed through the water vapor cloud to pick up moisture, undergoes a marked change in direction and then passes through the outlet opening. The larger water droplets and air borne particles, being relative heavy, resist the change in direction and are separated from the main air stream, so that the air, which is discharged from the outlet opening, contains moisture in only the most finely divided form and is cleansed of substantially all foreign particles. To insure the addition of a maximum amount of moisture to the air, the atomizing means also includes a heating element. The heating element, in addition to contributing to the formation of the water vapor cloud, increases the temperature of the air to be treated and correspondingly increases its moisture carrying capacity.
In U.S. Pat. No. 5,014,338, inventor Glucksman, which issued May 7, 1991, there is described a portable warm-air humidifier, the components of which are enclosed in a housing. The components include an evaporation chamber in the shape of an inverted cup which has a steam outlet in its top and contains an electric heating element positioned at a short distance above its open bottom. The chamber bottom and the heating elements are immersed in water contained in the main compartment of an open, removable tray, having a smaller filling compartment communicating with the main compartment. The tray may be removed from the housing for cleaning. The neck of an inverted, removable jug filled with water is placed into the filling compartment, and water fills the tray until its level reaches the lower rim of the jug's neck. A blower is mounted above the evaporation chamber and delivers cool air through a duct which communicates with the evaporation chamber via its steam outlet, and humidified air is blown back into the room. The humidifier also contains a control element to prevent damage to the heating element and signal lamps warning an attendant to refill the jug with water. The humidifier may also include a removable drawer.